he'll team up with another high-profile supporter, former president bill clinton. ohio is a critical battleground state and the race between obama and mitt romney is now neck and neck in that battleground state. >>> meanwhile, there has been a troubling incident at president obama's campaign office in denver, colorado. police say a shot was fired at the office yesterday, shattering a window. people were inside the building at the time. luckily, no one was hurt. police say they don't have a suspect yet, but they are investigating a possible suspicious car at the scene. >>> cnn's shannon travis joining me now with the latest on that investigation. what are authorities willing to say right now? >> well, actually, fred, they're not willing to go further than what you just said. we called around to the campaigns themselves. they're referring us to police, and police are only pretty much divulging those details you mentioned. a single shot was fired. this window was shattered at this obama campaign office there in denver, and that there is a possible vehicle of interest,